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Anaerobic treatment of high nitrogen, high TDS, industrial wastes

page 188

21 ANAEROBIC TREATMENT OF HIGH NITROGEN, HIGH
TDS INDUSTRIAL WASTES
Shahab Shafai, Research Assistant
Jan A. Oleszkiewicz, Associate Professor
Department of Civil Engineering
University of Manitoba
Winnipeg, Manitoba
Canada R3T 2N2
G. D. Hooper, Engineer
MacLaren Engineers, Inc.
Winnipeg, Manitoba
Canada R3L 2T4
INTRODUCTION & OBJECTIVES
Effluent from a pharmaceutical plant was treated anaerobically. The wastewater was from an
estrone manufacturing plant and contained significant quantity of spent pregnant mare's urine
(PMU). The plant operates during winter months only from October to March. The process block
diagram is similar to the one shown in Figure 1. The raw PMU goes through a succession of chemical
processes of extraction-evaporation-acidification. The effluent wastewater characteristics are listed in
Table I. The spent PMU is very high in total dissolved solids (TDS), nitrogen, and organics. The
wastewater from this plant is discharged into the city main sewer and along with the domestic sewage
from the city is treated in a combination of an extended aeration activated sludge plant and a lagoon
system. The municipal wastewater treatment plant (MWTP) is organically overloaded. As part of the
sewage treatment facilities expansion, this study was to determine the feasibility of a separate pretreatment of the spent PMU on site to achieve ammonification and some organics removal by anaerobic
means thus facilitating nitrification in the MWTP by lowering the presently high organic loadings.
The specific objectives were to examine the minimum dilution required to achieve ammonification,
the extent of COD removal in an anaerobic process, and the possibility of inhibition and/or toxicity
due to total dissolved solids (TDS) and/or free ammonia. An approximately three month period was
allotted for the study, and it was run under quasi-steady-state conditions.
EQUIPMENT & METHODS
Two types of anaerobic reactors were used: continuously fed upflow reactors and three series of
batch reactors. Parallel to this study, separate biomethanation potential (BMP) tests were run.
Continuous Flow Studies
In continuous flow studies, three parallel upflow anaerobic reactors were used (Figure 2). The
reactors were made of plexiglass. Reactors 1 and 2 were upflow sludge blanket (USB) reactors with
conical bottoms. Reactor 3 was an anhybrid reactor of cylindrical shape with its upper 75% of volume
filled with plastic rings one inch in diameter. This reactor was based on the original concept introduced earlier by DLA (1).
Each reactor was connected to a split box, installed to equalize pressure between the recycle line and
the reactor top. The recycle line allowed blending of the raw and the recycled wastewater just before
the influent end of the reactors. Each reactor was equipped with variable speed and recycle pumps.
The reactors were placed in a walk-in environmental chamber kept at 35°C. Three separate feed
buckets and three separate effluent storage tanks were housed in an adjoining environmental chamber
which was maintained at 5°C. Gas was evacuated through a gas lock flask, allowing visual inspection
of gas production, and a Triton low flow gas meter. Tygon tubing was used for all gas and liquid lines.
188

21 ANAEROBIC TREATMENT OF HIGH NITROGEN, HIGH
TDS INDUSTRIAL WASTES
Shahab Shafai, Research Assistant
Jan A. Oleszkiewicz, Associate Professor
Department of Civil Engineering
University of Manitoba
Winnipeg, Manitoba
Canada R3T 2N2
G. D. Hooper, Engineer
MacLaren Engineers, Inc.
Winnipeg, Manitoba
Canada R3L 2T4
INTRODUCTION & OBJECTIVES
Effluent from a pharmaceutical plant was treated anaerobically. The wastewater was from an
estrone manufacturing plant and contained significant quantity of spent pregnant mare's urine
(PMU). The plant operates during winter months only from October to March. The process block
diagram is similar to the one shown in Figure 1. The raw PMU goes through a succession of chemical
processes of extraction-evaporation-acidification. The effluent wastewater characteristics are listed in
Table I. The spent PMU is very high in total dissolved solids (TDS), nitrogen, and organics. The
wastewater from this plant is discharged into the city main sewer and along with the domestic sewage
from the city is treated in a combination of an extended aeration activated sludge plant and a lagoon
system. The municipal wastewater treatment plant (MWTP) is organically overloaded. As part of the
sewage treatment facilities expansion, this study was to determine the feasibility of a separate pretreatment of the spent PMU on site to achieve ammonification and some organics removal by anaerobic
means thus facilitating nitrification in the MWTP by lowering the presently high organic loadings.
The specific objectives were to examine the minimum dilution required to achieve ammonification,
the extent of COD removal in an anaerobic process, and the possibility of inhibition and/or toxicity
due to total dissolved solids (TDS) and/or free ammonia. An approximately three month period was
allotted for the study, and it was run under quasi-steady-state conditions.
EQUIPMENT & METHODS
Two types of anaerobic reactors were used: continuously fed upflow reactors and three series of
batch reactors. Parallel to this study, separate biomethanation potential (BMP) tests were run.
Continuous Flow Studies
In continuous flow studies, three parallel upflow anaerobic reactors were used (Figure 2). The
reactors were made of plexiglass. Reactors 1 and 2 were upflow sludge blanket (USB) reactors with
conical bottoms. Reactor 3 was an anhybrid reactor of cylindrical shape with its upper 75% of volume
filled with plastic rings one inch in diameter. This reactor was based on the original concept introduced earlier by DLA (1).
Each reactor was connected to a split box, installed to equalize pressure between the recycle line and
the reactor top. The recycle line allowed blending of the raw and the recycled wastewater just before
the influent end of the reactors. Each reactor was equipped with variable speed and recycle pumps.
The reactors were placed in a walk-in environmental chamber kept at 35°C. Three separate feed
buckets and three separate effluent storage tanks were housed in an adjoining environmental chamber
which was maintained at 5°C. Gas was evacuated through a gas lock flask, allowing visual inspection
of gas production, and a Triton low flow gas meter. Tygon tubing was used for all gas and liquid lines.
188